In biological and biochemical screening systems that employ plant tissue, it is important that the growth of the plant tissue be promoted. Growth of the plant tissue is affected by several factors which include the amount and type of nutrients supplied to the tissue, the physical support provided for the tissue, the temperature of the tissue environment and the amount of light delivered to the plant tissue. With respect to the availability of light, most screening systems employ artificial light which can be controlled and is not subject to the vagaries of the weather. In addition, the screening systems typically employ plates wherein each plate defines multiple wells. Each of the wells holds and isolates a separate tissue sample so as to avoid contamination with other tissue samples and the environment.
Existing systems for promoting plant tissue growth typically employ a rack, or “hotel,” having multiple shelves each holding a plurality of the multiple well plates. Above each shelf is a bank of incandescent or fluorescent lights providing illumination to the multi-well plates and the tissue contained therein. The rack however, has a limited vertical stacking capacity as the lights must be kept a safe distance from the plant tissue to avoid excessive build-up of heat and because the incandescent and fluorescent lights are relatively bulky. Each shelf and light bank combination requires about one foot of vertical space, limiting a normal room with eight feet high ceilings to seven or eight shelves. In addition, incandescent or fluorescent lights are not very energy efficient, requiring about 4.4 watts of power per multiple well plate. Such large space and power requirements, coupled with cost constraints, tend to limit the density of the rack and the throughput of plant tissue screening systems.
Therefore, it would be advantageous to have a system for promoting the growth of plant tissues that can supply sufficient light to plant tissue in multiple well plates while also allowing for an increase in throughput of the screening operation. In particular, it would be advantageous to have a system for promoting the growth of plant tissues that does not occupy an excessive amount of space, nor require the use of large amounts of power per plate.